Positive displacement pump



Nov. 7, 1961 F. B. BURT POSITIVE DISPLACEMENT PUMP Filed April 19, 1957 7 Sheets-Sheet 1 +1, A 24 Z 40 36 1401.: r0 Accumum'ronw VANE $LOT ALWAY HIGH PR E 5 SURE FARLOW 5%31 IE. 5. BY

ATTORNE Nov. 7, 1961 F. B. BURT 3,007,419

POSITIVE DISPLACEMENT PUMP Filed April 19, 1957 7 Sheets-Sheet 2 ZEAKAGE E1 6 N 4i H fi 5 .6.5 v FAR 5. F/ $T.

F. B. BURT POSITIVE DISPLACEMENT PUMP Nov. 7, 1961 7 Sheets-Sheet 3 Filed April 19, 1957 INVENTOR. FAgLow B. BURT. WM fi- ATTOR EY.

Nov. 7, 1961 F. B. BURT 3,

POSITIVE DISPLACEMENT PUMP Filed April 19, 1957 7 Sheets-Sheet 4 v LEAKAGE.

TIM E INVENTOR.

g FAIQLOW B.BURT

A TTURN Y.

Nov. 7, 1961 F. B. BURT POSITIVE DISPLACEMENT PUMP 7 Sheets-Sheet 5 Filed April 19, 1957 TIME. 3 .15.

FARLOW B. BURL-T.

Nov. 7, 1961 F. B. BURT POSITIVE DISPLACEMENT PUMP Filed April 19, 1957 7 Sheets-Sheet 6 xii-Maia Nov. 7, 1961 F. B. BURT 3,007,419

POSITIVE DISPLACEMENT PUMP Filed April 19, 1957 '7 Sheets-Sheet 7 INVENTOR.

FARLOW B. BURT.

2% fim United States Patent Filed Apr. 19, 1957, Ser. No. 653,846 11 Claims. (Cl. 103136) The present invention relates to positive displacement pumps generally; and more particularly to means for smoothing out pressure pulsations in the discharge of these pumps.

The various positive displacement pumps with which I am familiar (including gear, sliding vane, radial piston, and axial piston pumps) all produce pressure pulsations in their discharge for one of two reasons: (1) these pumps by their very nature may have instantaneous discharge rates which vary throughout the pumping cycle; and (2) where the device is used in high pressure systems, pressure surges will be developed when the pumps individual fluid confining chambers (that have been filled with fluid at suction pressure) are communicated to the pumps discharge because of compressibility of the fluid.

An object of the present invention is the provision of a new and improved positive displacement pump having means which will bleed liquid from the discharge portion of the pump in a manner offsetting the previously referred to pressure surges.

Another object of the invention is the provision of a new and improved pump having means of the above described type which comprise valve ports formed in cooperating sliding sealing surfaces of the rotor and an adjacent member such that the timing of the bleeding operation will be accurately and simply maintained with respect to the pumps cycle of operation.

Another object of the invention is the provision of a new and improved positive displacement pump comprising an accumulator reservoir maintained at a pressure approaching pump discharge pressure, means for communicating the accumulator to the pumps individual pressure chambers at a time when they are filled with liquid but valved off from both the suction and discharge por tions of the pump to pressurize the individual chambers before they are communicated to discharge (thus partially eliminating pump discharge surges), and valve means operated in phase relation with the pumps rotor to bleed small amounts of liquid out of the pumps discharge in a manner offsetting remaining pulsations and smoothing out the fluid discharged from the pump.

A further object of the invention is the provision of a new and improved sliding vane positive displacement pump of a design having constant theoretical volume displacement per rotor cycle, and in which its rotor and casing have side surfaces which are in sliding sea-ling engagement and are provided with suitably shaped ports to accomplish the above objects.

A more particular object of the invention is the provision of a new and improved radial piston pump comprising a generally cylindrical pintle and an annular rotor surrounding the pintle, which members are provided with cooperating sliding sealing surfaces in which suitable porting is provided laterally of the cylinders to partially pressurize the individual cylinders prior to the time they are valved to discharge, and to bleed fluid from them when they are opened to discharge in a manner offsetting surges of pressure and thus smoothing out the discharge of the pump. I

Further objects of the invention will become apparent to those skilled in the art to which the invention relates from the following description of several preferred embodiments described with reference to the accompanying drawings forming a part of this specification, and in which:

FIGURE 1 is a cross-sectional view of a sliding vane pump embodying principles of the present invention;

FIGURES 2, 3 and 4 are cross-sectional views taken upon the same cross-section line indicated in FIGURE 1,

but showing the rotor in different positions;

FIGURE 5 is a fragmentary cross-sectional View taken on the line 55 of FIGURE 2;

FIGURE 6 is a fragmentary cross-sectional view similar to FIGURE 5 but showing a slightly different arrangement of porting;

FIGURE 7 is a diagrammatic view of a time-leakage curve which the structure shown in FIGURE 6 provides;

FIGURE 8 is a fragmentary cross-sectional view similar to that shown in FIGURE 5 but showing a different porting arrangement;

FIGURE 9 is a time-leakage curve which the structure shown in FIGURE 8 provides;

FIGURE 10 is a fragmentary cross-sectional View of structure similar to that shown in FIGURE 5 but showing a still further modification of porting;

FIGURE 11 is a time-leakage curve of the structure shown in FIGURE 10;

FIGURE 12 is a still further modification of the po ing shown in FIGURE 5;

FIGURE 13 is a time-leakage cuive for'the structure shown in FIGURE 12;

FIGURE 14 is a cross sectional view of a radial ball piston pump but showing its pintle in elevation;

FIGURE 15 is a cross-sectional w'ew taken on the line 15-15 of FIGURE 14;

FIGURE 16 is a cross-sectional view taken on the line 16-16 of FIGURE 14; and

FIGURE 17 is a cross-sectional view taken on the line I7-17 of FIGURE 14 and showing the pintle, rotor and cam members only.

Although other embodiments of the invention can be made incorporating the principles set forth and covered by my claims (which embodiments may have their own unique advantages), the preferred embodiment shown in FIGURES 1 through 4 is specifically ad-apted for use in automotive power steering systems wherein it has particular advantages. As previously indicated, most positive displacement pumps discharge the liquid being pumped in a manner producing pressure pulsations, or surges, either because the pumps do not have a constant rate of discharge or because of the compressibility of the fluid being pumped. The pressure surges so created produce noise and vibrations in the systems to which the pump is connected which noise and vibration is transmitted to the drivers compartment of the vehicle through the steering column and/ or frame of the vehicle.

The pump shown in FIGURE 1 generally comprises a casing or body member A formed by means of a generally annular center section 20, and opposite end closure mcm- =bers 22 and 24 to provide an internal pump chamber 26. The opposite end closure members 22 and 24 form generally flat parallel end surfaces for the internal pump chamber 26, which surfaces provide a sliding sealing engagement with respect to a cylindrically shaped roto-r'B positioned within the pump chamber 26.

The internal surface of the center section 20 of the pump casing A is provided with a plurality of valleys 28 which are separated by means of lobes 30 which sealingly abut the outer surface of the rotor B to provide a plurality of uniformly spaced individual pumping chambers 32 spaced about the rotor. The rotor member B is provided with four uniformly spaced radical slots 34 each of which receives a sliding vane 36 which is biased outwardly into engagement with the internaltcamming surface 38 of the pump to sweep liquid from the individual pumping chambers 32 during rotation of the rotor member B. Fluid swept from the individual pumping chambers 32 passes through radial discharge slots 40 positioned in the rotor member B just forwardly of each sliding vane 36 to a transverse drilling 42, in the rotor member B at the inner end of each of the radial slots 34. Pump discharge pressure is therefore supplied to the inner end of each of the sliding vanes 36 tending to force the sliding vanes into more firm engagement with the internal camming surface 38 of the pump. Annular discharge grooves 44 and 46 are formed in the end closure members 22 and 24 respectively of the casing for communication with the respective ends of the transverse drillings 42. Discharge flow is therefore free to flow around each of the annular grooves 44 and 46 to distribute pressure equally upon both sides of the rotor and thence to a pump discharge connection 48 communicating with the annular discharge groove 44.

Fluid is added to each of the individual pumping chambers 32, from which fluid has been previously swept by the sliding vanes 36, by means of radial inlet drillings 50 positioned in the rotor member B immediately behind each of the sliding vanes 36. The inner end of the radial drillings 50 open into a centrally located suction chamber 52 in the rotor member B, which chamber receives fiuid from the suction connection 54 of the pump in the closure member 22 of the casing A. The cooperating side surfaces of the end closure members 22 and 24, and rotor member B, have a sufiiciently close fit to effect a running seal between the discharge grooves 44 and 46 and the inlet chambers of the rotor and easing member. The rotor member B is adapted to be driven by means of a shaft C splined to the center of the rotor member; and the internal camming surfaces 38 are of such a configuration that the volumes swept by each of the sliding vanes 36 during the rotation of the rotor will at all times be constant. The particular contour used for the camming surface 38 is a sinusoidal one; and for a more complete description of the construction and operation.

of the structure so far described, reference may be had to the Burt et al. application 623,144.

The pump shown in FIGURE 1 is provided with an accumulator reservoir or sink for the purpose of pressurizing the individual pumping chambers at a time when they are isolated from both the suction and discharge passages of the pump-such that when the individual pumping chambers are communicated to the discharge passageways of the pump, the amount of fiowback into the pumping chambers due to the compressibility of the liquid will be greatly reduced. The accumulator reservoir or sink D is formed by means of an internal chamber 56 in the end closure member 24 surrounding the drive shaft C of the pump. The accumulator reservoir D is isolated from the shafts rotating structure by means of a sleeve 58 which is pressed into the opening 60 in the closure member 24 in which the drive shaft C is positioned. The drive shaft C is formed in two sections an outer section 62 tightly journalled in the end closure member 24, and an inner section 64 adapted to tolerate a small amount of angular movement between the rotor member B and the outer or driven shaft section 62 of the pump. The outer shaft section 62 is journalled at its inner end by a raised portion 66 which slidingly abuts the inner surface 68 of the sleeve 58, and is journalled at its outer end by means of anti-friction means 70 received in a counterbore 72 in the outer end of the axially extending opening 60. The anti-friction means 70 is held in place by the snap ring 74. The inner shaft section 64 is splined at both ends to provide a driving connection with respect to the rotor B, and shaft section 62, respectively; and is retained against axial movement by means of a raised cylindrical section 76 which is positioned between a shoulder 78 in the sleeve 58, and the inner end of the outer shaft section 62. The outer shaft section 62 is retained against removal from the pump by means of a wire snap ring 89 which is seated in a groove 82 in the shaft section 62, and which snap ring abuts the inner end of the anti-friction means 70. An

annular seal retaining washer 84 is positioned between the anti-friction means and the inner end of its counterbore 72, and an annular U-packing 86 is positioned between the washer 84 and the outer end of the sleeve 58 to prevent the leakage of oil out around the shaft structure.

The individual pumping chambers 32 are pressurized from the accumulator reservoir D by means of drilled passageways 88 (one for each valley 28 of the pump) extending between the accumulator chamber 56 and the internal pump chamber 26. The drilled passageways 88 open into the portion of the side walls of the chamber 26 which are sliding sealingly abutted by one side surface of the rotor member B. A plurality of radially extending grooves 90 (one for each vane) is positioned in this sliding sealing side surface of the rotor B in a manner adapted to communicate the reservoir D with the individual pumping chambers 32 when the grooves 90 are in registry with the drilled passageways 88. The radial extending grooves 90 are so positioned relative to the suction and discharge portion of the rotor so as to be in reg stry with the drilled passageways 88 at a time when the individual pumping chambers are isolated from both the suction and discharge passageways of the rotor. The drilled passageways 88 and radially extending grooves 90 will preferably be so constructed and arranged that the edge of the groove 90 will start to communicate with the passageway 88 just after the time that the suction groove 50, which has previously filled the pumping chamber, has moved past the sealing edge of the forwardly positioned land 30 of the pumping chamber to be pressurized (such a position is shown in the upper left hand corner of FIGURE 2). In this rotor position, the sliding vane 36, which is about to sweep the pumping chamber involved, will assume a position as shown in FIGURE 2 and as indicated in each of the FIGURES 2, 3, and 4 by the numeral 2. Continued rotation of the rotor B causes the groove 90 to move over the drilled passageways 88 thereby permitting fiow from the accumulator into the pumping chambers being pressun'zed. Just prior to the time that the leading edge of the discharge groove 40 of the trailing vane about to sweep the pumping chamber registers with the sealing edge of the trailing lobe 30, the radially extending grooves 90 will move out of registry with the drilled passageways 88 (this position is shown in FIGURE 3 and is indicated by the numeral 3 in each of the FIG- URES 2, 3, and 4). It will therefore be seen that pressurizing of the individual pumping chambers must take place while the rotor is moving between the positions 2 and 3, and that the drilled passageways 88 and grooves 92') will be so proportioned as to use as much of this rotor movement as is feasible.

According to further pinciples of the invention, a side stream of fluid is bled out of the pump discharge in amounts and at time intervals which will offset the pressure surges created in the pump discharge when the individual pumping chambers 32 are communicated therewith. Inasmuch as the accumulator reservoir D will not always be maintained at a pressure equaling the pressure discharge of the pump, a slight amount of backfiow due to compressibility of the fiuid will be experienced when the individual pumping chambers 32 are first communicated to the discharge of the pump. This will produce a periodic and rhythmical pressure pulsation or surging in the pump discharge, which pulsations will have a frequency generally proportional to the number of pumping chambers and the speed of rotation of its rotor. The precise configuration of these pressure pulsations or waves will vary depending upon the type of positive displacement pump involved (gear, sliding vane, radial or axial piston), and will vary to some degree depending upon the formation of the pump discharge chambers and/ or the system to which the pump is connected. In all cases the timerate pattern or configuration of the pulsations can be accurately determined by means of an oscilloscope or other suitable laboratory means.

The means provided in the pump shown in FIGURE 1 for bleeding fluid out of the pump discharge in amounts offsetting these pressure surges, comprises a plurality of ports or grooves 92 in the sliding sealing surface of the rotor B positioned in such manner as to register with the drilled passageways 88 subsequent to the time that the individual pumping chambers 32 are first communicated with the associated discharge slot 40 of the sliding vane 36 which forces the liquid out of the pumping chamber involved. Pressure flowback into the pumping chambers 32 creates the valleys or low points in the pump pressure discharge curve during the time that the rotor is moved from the position shown in FIGURE 3 to the position shown inFlGURE '4 (and as indicated by the numerals 3 and 4 of each of the FIGURES 2, 3 and 4). The start of the discharge stroke for the pumping chamber involved occurs at a time when the trailing sliding vane 36 is positioned over the center of the trailing lobe 30; and continues while the sliding vane 36 moves through the pump ing chamber to the center of the lobe 30 on the other or downstream side of the pumping chamber involved. The rising portion of the pump pressure discharge curve will occur generally over the interval in which the sliding vane sweeps the individual pumping chamber.

The porting or grooves 92 are brought into communication with the drilled passageways 88 at some time interval after the appropriate sliding vane 36 starts to sweep the individual pumping chamber involved. This is shown in the upper left-hand corner of FIGURE 4 wherein the groove 92 is out of registry with the passageway 88. Shortly thereafter the leading edge of the groove 92 is brought into registry with the passageway 88 to start the process of bleeding liquid out of the pump discharge.

The bleed ports or grooves 92 are connected to the pump discharge system by means of a passageway or port 94 communicating its trailing edge with the radial discharge slots 40. The radial discharge passageway 94 and the bleed port or grooves 92 are so shaped as to vary the amount of fluid bled outof the pump discharge in a manner offsetting the pressure pulsations. The instantaneous rate of fluid flow through the groove 92 and port 94 will be controlled by the cross-sectional area of the groove 92 in combination with the length of groove intermediate the passageway 88 and the inlet port 94; and the maximum amount or peak value of the flow experienced when the inlet port 94 is in registry with the passageway 88 will be controlled by the sizes of either one or both of the passageways 88 and 94. As a general rule a groove 92 of constant predetermined cross-section will give a uniformally increasing rate of leakage as the rotor is rotated; and'the slope of the time-leakage curve can be changed by changing the cross-sectional area of the groove 92. Where the change in the cross-sectional area of the groove 92 is abrupt, sharp changes in the slope of the time-leakage curve will be experienced; and the over-all length of the time-leakage curve will be controlled by the over-all length of the groove 92.

FIGURES 6 through 13 show several forms of leakage groove, and the type of time-leakage curve which they provide (the even number figures showing the construction of the groove, and the next succeeding odd number figure showing the time-leakage curve which it provides). These'veral grooves shown utilize the principles above set forth, and show the manner in which the principles can be combined to provide time-leakage curves of practically any configuration. These time-leakage curves, of course, should be tailored to provide a time-leakage curve shape which generally corresponds to the shape of the pressure pulsations of the pump in which the leakage grooves are to be used; such that the instantaneous rate of leakage so provided is proportional to the instantaneous pressure intensity of its impulses or surges.

FIGURE 6 shows a bleed port configuration having a substantially constant uniform cross-section for the full length of the groove, and a pressure inlet port adjacent its trailing edge. This type of groove when passing over a suitable outlet port produces a time-leakage curve having a substantially constant or uniform slopeindicating that the rate of discharge for the bleed port builds up at a substantially constant rate, and thereafter drops oif sharply when the trailing edge of the groove moves past the cooperating outlet port.

FIGURE 8 shows a bleed port configuration in which the pressure inlet passageway or opening is positioned in approximately the center of the groove. With such a configuration, the leakage builds up at a generally uniform rate until the pressure inlet passage is in register with the outlet port; and thereafter, decreases at a substantially uniform rate until the trailing edge of the groove passes the outlet port. 7

FIGURE 10 shows a stepped bleed groove configuration in which the configuration of the cross-sectional groove is changed in a series of steps to provide a changing rate of discharge. As the leading edge of the discharge groove 92 opens into registry with the outlet port, a generally rapid build up of flow is initiated until the outlet port is completely opened. Thereafter, the leakage rate increases at a substantially constant rate until the deeper portion of the groove moves into registry with the outlet port. Thereafter the discharge flow increases at a faster rate than was provided by the first stepped portion of the groove until the pressure inlet port begins to move into registry with the outlet port. The discharge rate gradually changes to a maximum rate, which continues for a short time, until the trailing edge of the port begins to move into registry with the outlet port. The flow rate continues to gradually decrease until the trailing constant crosssectional area of the groove is in registry with the outlet port, and thereafter the discharge flow decreases at a substantially constant rate until the trailing edge of the groove begins to choke off the flow out through the discharge port.

FIGURE 12 shows a bleed port having two pressure inlet openings. The time-leakage curve for such a configuration of bleed port will have two peaks spaced apart in accordance with the spacing of the grooves inlet openings. The bleed groove shown in FIGURE 2 is provided with a substantially constant uniform cross-section through its entire length to give rising and falling portions of the curve having substantially the same slope or rate of change. The rate of discharge builds up to a peak at about the time that the first inlet passage of the groove 92 is in registry with the outlet port; and there after decreases at approximately the same rate of change until the discharge port is approximately centered between the two inlet ports 94 and 96. When the discharge port 88 is intermediate the inlets 94 and 96, flow of course can proceed from both of the inlet ports through the outlet port to create a minimum flow when the outlet port 88 is approximately centered between the two inlets. Thereafter the flow increases again as the inlet port 94 moves closer to the outlet port 88 until the inlet port 94 is in registry with the outlet port, at which time a peak is again reached. Thereafter the flow will decrease again until the trailing edge of the groove 92 moves past the outlet port 88. Peaks of different intensity could be provided by regulating the sizes of the branch passageways 94 and 96; and other minor fluctions in the curve can be provided by varying the depth or width or both of the various sections of the groove 92. Tapered leading and trailing edges of the groove 92 will likewise change or smoothen out the leading and trailing edges of the time-leakage curve.

As a general comment, the principles set forth above can be used to provide a shape of time-leakage curve which generally corresponds to the shape of the pressure pulsations as determined by an oscilloscope or other means. Thereafter cut and try means can be used to vary the shape and cross-section of the groove at appropriate points, and/or the size of the inlet and outlet openings may be changed to match the time-leakage curve of the pump whose discharge is to be smoothened out.

The operation of the pump shown in FIGURE 1 causes fluid to flow through the pump inlet port or suction connection 54 to the suction chamber 52 of the rotor B; whereupon, flow proceeds from the inlet drillings 50 to the individual pumping chambers 32 as the inlet drillings 50 are rotated past the pumping chambers. Each of the pumping chambers 32 are of course separated by lobes 30 which are adapted to sliding sealingly engage the outer surface of the rotor B in such manner as to valve off each of the pumping chambers for an interval of time after an inlet groove 50 has been moved past one of the chambers separating lobes 30 and prior to the time that the following discharge slot 40 is moved into registry with the other separating lobe 30 for the chamber. During this portion of the time that the individual pumping chambers are valved ofi from both the suction and discharge portions of the pump, the individual pumping chamber is pressurized by means of fluid from the accumulator chamber 56 by means of the passageway 88 and the radially extending groove 90 which are positioned in the sliding sealing side surfaces of the internal pump chamber, and rotor, respectively. During this interval, the groove 90 is brought into registry with the passageway 88-permitting flow from the accumulator 56 to raise the pressure in the isolated pump chamber from its original suction pressure to a pressure approximately that at which the accumulator is maintained. Immediately thereafter, the discharge slot 40 is brought into communication with the pumping chamber to connect the pumping chamber with the discharge portion of the pump. The trailing sliding vane 36 thereafter sweeps the fluid out of the pumping chamber through the discharge slot 40, transverse drilling 42, annular grOOves 44 and 46, to the discharge connection 48 of the pump.

The pressurized of the individual pump chambers prior to their being valved to discharge appreciably helps to reduce the amount, or intensity of the pressure pulsations produced in the pump discharge. Inasmuch as the pressure in the accumulator cannot be maintained exactly at pump discharge pressure, some pressure pulsations are still produced whenthe individual pumping chambers are connected to discharge. According to the principles of the present invention suitable bleed passages 92 are utilized to bleed off fluid from the discharge of the pump in amounts, and at time intervals which will offset the remaining pulsations in the pump discharge. Shortly after the sliding vane starts to force fluid out of a filled pumping chamber 32, the bleed groove 92 is moved in registry with the drilled passageway 88 communicating with the reservoir D. This causes fluid to flow out of the discharge of the pump through the inlet port 94, groove 92 to the drilling 88, thereby replacing fluid previously withdrawn from the accumulator D to maintain the reservoir at its generally predetermined pressure. The size and shape of the grooves 92 and 94 are of course varied as previously explained to provide a timeleakage curve which will generally match the pressure pulsation curve of the pump so as to offset the pulsations and smoothen out the pressure of the fluid discharged from the pump. Inasmuch as the pump shown in the drawing is hydraulically balanced such that the cycle of operation of opposite vanes is identical, only two pressure bleed grooves 92 need be used to smoothen out the pump operation.

While the preferred embodiment uses the pressure bleeding process to replenish the accumulator chamber, this need not be done; and if preferred, the bleed stream can be returned directly to the suction of the pump or even to an external source.

FIGURES 14, 15, 16 and 17 show the invention as embodied in a radial ball piston pump which generally comprises a body member E having an internal chamber 102 therein in which an annular rotor F is jonrnalled about an axially extending pintle G which projects into the internal chamber 102 from one end wall of the pump. The opposite end wall 106 of the pump is made in the form of a removable cover member suitably bolted in place; and the annular rotor F is adapted to be rotated about the pintle by means of a drive shaft 108 journalled in the cover member 106. The inner end of the drive shaft 108 is splined to a drive plate 110 positioned over the adjacent end of the pintle, and the outer edges of which are fastened to the annular rotor F by means of a plurality of machine screws 112 only one of which is shown.

The annular rotor member F is provided with a plurality of radially extending openings 114 therethrough the radially outer ends of which are accurately counterbored to form cylinders 116 in which individual ball pistons 118 are positioned. The ball pistons 118 are retained within the cylinder by means of an annular camming member H which extends around the outer surfaces of the rotor and on which the balls 118 are adapted to roll. The annular camming member H shown in the drawing utilizes a race 120 of a commercially obtainable anti-friction bearing, pressed into a support member 122 which is suitably guided and supported for eccentrio movement with respect to the rotor F.

a The pump shown in the drawing is adapted to be sup plied with oil from a reservoir 124 which is bolted directly t0 the top surface of the pump. Oil from the reservoir passes through a vertical opening 126 in the body member E to a longitudinally extending drilling 128 in the axially extending pintle G. The top surface of the pintle G directly beneath the annular rotor F is notched out as at 130 to provide inlet communication between the inner end of the cylinders 116 and the inner end of the longitudinally extending drilling 128; and a venturi section 132 is pressed into the longitudinally extending drilling 128 between the inlet passage 126 and the notch 130 supplying the rotor. The particular embodiment shown in the drawing utilizes a pressurized suction wherein the fluid from the inlet passage 126 is forced into the throat of the venturi section 132 to the cylinders 116 by means of a pressure impinging stream presently to be described.

The radial piston pump shown in the drawings is adapted to be driven clockwise as seen in FIGURE 15. The annular camming member H is supported for eccentric movement with respect to the annular rotor F by means of an abutment pin 134 recessed into the lower end of both the body member E and the support member 122 in such manner as to limit all but a rocking movement of the camming member H with respect to the rotor F. Maximum displacement of the pump will be provided when the camming member H is in the position shown in FIGURE 15 of the drawing. With the camming member H in the position shown, the ball pistons 118 will be in their innermost positions with respect to the cooperating cylinders 116 when the inner end of the cylinders 116 are moved out of engagement with the land portion 136 of the pintle into communication with the inlet groove 130 on the upper surface of the pintle. The positioning of the camming member H is such that centrifugal force moves the ball pistons 118 radially outwardly in their cooperating cylinders 116 as the balls roll around the race 120 to a position approximately from the start of the inlet stroke. As the ball pistons approach their outward limit of travel, the inner end of the cylinders 116 move out of communication with the inlet groove 130 to a position wherein a land 138 valves off or completely isolates the cylinders 116 from both suction and discharge.

Continued rotation of the rotor during the second half of each revolution causes the ball pistons 118 to roll around the lower half of the race 120, thereby causing the pistons 118 to be moved inwardly to their most 9 inwardly or starting position. Just after the time that the ball pistons 118 start to move inwardly, the inner ends of the cylinders 1-16 move ofi? the land 168 into communication with the discharge groove 140 in the lower surface of the pintle G. The discharge groove 140 is quite similar to the inlet groove 130 (extending over a similar arc of the pintle); but is separated from the inlet groove 130 by the land portions 136 and 138. Fluid forced into the discharge groove 140 by the inward movement of the ball pistons 118 passes through a longitudinal discharge drilling 142 in the pintle G to a transverse drilling 144 leading to a discharge chamber 146 in the body member E. Some discharge fluid is used for the pressurizing of the pump inlet stream by means of a transverse drilling 148 communicating the longitudinal discharge drilling 142 with a nozzle 150 in the inlet drilling 128. The passage 148 opens into an annular groove 152 in the nozzle 150; and a transverse drilling 154 between opposite sides of the recess or groove 152 communicates with a small longitudinal drilling 156 which directs the high pressure stream into the throat of the venturi section 132. Fluid being discharged from the pump passes through an annular filter 158 held into engagement with the bottom end of the discharge chamber 146 surrounding its inlet 160 by means of a retainer 162 and a coil spring 164. The coil spring 164 is in turn held in place by a threaded outlet fitting 166 screwed into the outer end of the discharge chamber 146. The fitting 166 is provided with :a centrally located discharge opening 168 therethrough containing a check valve 170 and cooperating valve seat 172 for the prevention of return flow through the pump. A bent wire 174 is inserted between the check valve 170 and a tube fitting 176 in the opening 168 to prevent the ball from restricting flow out of the discharge connection.

The rate of discharge of the pump shown in FIGURES '14 through 17 can be varied by shifting the camming member H with respect to the rotor F in a manner changing the eccentricity therebetween to vary the stroke of the individual pistons 118. Shifting of the carnrning member D is accomplished by means of a slide structure I comprising a cylindrically shaped slide 180 positioned in a bore 182 extending at substantially right angles to the displacement changing movement of the camming member H. The lower end of the cylindrically shaped slide 180 is provided with a milled slot 184 angularly disposed with respect to the direction of movement of the slide 180which slot receives a pin 186 fastened between the outer ends of a bifurcated or U-shaped bracket 188 which is brazed to the support member 122 of the camming member H. The slide 180 is biased downwardly by a coil spring 190 suitably positioned between the slide 180 and the bottom of the reservoir 124 which closes off the upper end of the bore 182. The camming member H is therefore normally urged into a position providing maximum displacement for the pump by the coil spring 190; and the displacement of the pump is decreased by means of a position 192 adapted to be biased against the lower end of the slide 180 to cause the slide to be moved upwardly. Upward movement of the slide of course causes the 'camming member H to be moved toward its concentric position thereby decreasing the stroke of the ball pistons 118.

The piston 192 is actuated by means of pressure from a control valve K which receives its pressure from the discharge of the pump. The control valve K comprises a bore 194 in the body member E in which a spool valve 196 is positioned in a manner permitting its lands to straddle a control port 198 in the side walls of the bore 194. The control piston 192 is positioned the upper end of a bore 200 positioned beneath the slide structure J; and the lower end of the bore 200 is communicated to the control port 198 through suitable passageways 202 in the body member E. The inner end of the control valve bore 194 is communicated with the discharge drilling 142 in the pump pintle C by a drilling 204; and the outer end of the bore 194 is communicated with the internal chamber 102 of the pump by means of an opening 206 in the body member E. The outer end of the spool valve 196 projects intoa spring chamber 208 where it is abutted by a spring retaining plate 210 which is biasedspinwardly by a coil spring 212. The outer end of the spring chamber 208 is closed off by a suitable sealing member 214 held in place by the threaded outlet fitting 166; and the spring chamber 208 is also vented to the internal pump chamber 102 by means of a drilling 216 in the body member. 'For a better understanding of the construction and operation of radial piston .pump so far described,- reference may be had to the Farlow B. Burt application Serial Number 649,370,.filed March 29, 1957.

Means similar to that described for the first described embodiment is also provided for the pump shown in FIG- URES 14 through 17. Pressure from an accumulator 220 is communicated to each of the cylinders 116 intermediate the time that they are valved off from the suction chambers of the pump and the time that they are connected to the discharge passageways of the pump. Control of the pressurizing of the individual pumping cylinders 116 is controlled in this instance by means of valve porting similar to that. used in the previous embodiment. In the present instance the control porting is positioned in the sliding sealing cylindrical surfaces of the pintle and rotor, respectively, which surfaces rotatably support the rotor member F. Angularly drilled passageways 222 (one for each of the cylinders 116) are provided in the rotor member F for the purpose of communicating each of the cylinder chambers 116 with the portion of the inner cylindrical surface of the rotor positioned to one side of the plane in which the cylinders are located. A pressure fill port 224 is provided in the pintle G adjacent the land portion 138 for registry with each of the angularly drilled passageways .224 as they revolve therepast. Pressure is supplied the fill port 224 from the accumulator 220 through a longitudinal drilling 226 in the pintle G, which intersects the drilling forming the pressure fill port 224 at one end, and which is communicated to the accumulator 220 at its other end by means of a transverse drilling 228.

Fluid pressure from the accumulator 220 is used to pressurize each of the cylinders 116 when the ball pistons 118 therein have reached their outermost of travel and during the time that each cylinder is valved 011 from both the inlet groove and the discharge groove by the land 136. Fluid pressure from the accumulator 220 is bled to each cylinder at this instance in a controlled amount by means of the drilling which forms the pressure fill port 224. Each of the angularly drilled passageways 222 in the rotor F are brought into registry with the fill port 224 at a time when the trailing edge of the cylinder openings 114 have moved out of communication with the inlet groove 130 of the pintle. The sizes of the passageways 222 and fill port 224 are such that the passageways in the fill port will move out of registry with each other just prior to the instant that a cylinder, which has been pressurized moves into communication with the discharge groove 140 of the pintle.v By this expedient each of the cylinders 116 are successively pressurized from the accumulator,. and are immediately thereafter valved to discharge before any appreciable leak down of pressure in the individual cylinders takes place.

The present embodiment is also provided with means similar to that of the previous embodiment for bleeding fiuid from its discharge at times and in amounts which will offset its discharge pulsations to smoothen out the fluid delivered by the pump. In the present embodiment, this is accomplished by a second set of porting in the cylindrical surfaces of the pintle and rotor member located in the plane containing the fill port 224, such that the angularly drilled passageways 222 may also be used for the bleed down operation. In the embodiment shown in the drawing, the bleed down porting'230 located in the pintle is adapted to register with the angularly drilled passageway 222 of a cylinder 116 immediately following the time that the cylinder is first valved to discharge. The precise angular position at which the registry of the passageway 222 and bleed down porting 230 begins to take place will of course be determined by the pressure pulsation curve of the pump as determined by an oscilloscope, or other suitable means. Inasmuch as three other cylinders 116 are also communicating with the discharge groove 140 during this same period of time, the bleed porting 230 could probably be advanced 45 90, or 135 to cooperate with anyone of these other cylinders 116 which are valved to discharge during the same period of time.

The bleed down porting 230 is provided with a bleed groove or recess 232 in the sliding sealing surface of the pintlewhich groove is constructed in accordance with the principles previously described with reference to the FIGURES through 13. The outlet port 234 for the porting 230 is formed by a transverse drilling communicating the groove 232 and the longitudinal drilling 226, in the pintle, which leads to the accumulator 220.

Operation of the pump should be readily discernible by those skilled in the art from the above description reciting the cooperation between the various elements. Suffice it to say that hydraulic fluid from the reservoir 124 passes through the inlet passageway 126 to the venturi section 132 where the impingement of a high pressure stream through the longitudinal drilling 156 into the throat of the venturi section produces a positive pressure in the inlet groove 130 of the pintle C. Rotation of the rotor B successively communicates the cylinders 116 with the inlet groove 130 during the portion of the rotor cycle wherein the ball pistons 118, which are in rolling contact with the camming member H, move radially outwardly in their cylinders. Outward movement of the ball pistons 118 causes a quantity of fluid to be added to each cylinder while the cylinders are communicated to the inlet groove 130; and at approximately the time that the ball pistons 118 have reached their outward limit of travel, the inner openings 114 of the cylinder slide over the land portion 138 of the pintle to isolate the cylinders from communication with both the inlet and outlet systems of the pump. Shortly after the cylinders 116 become valved off from the inlet groove 130 and prior to the time that the cylinders are communicated with the discharge groove 140 of the pintle, each cylinder is pressurized with fluid from the accumulator 124 by the rotation of the cylinders angular-1y drilled passageway 222 into communication with the pressure fill port 224 of the pintle. Each cylinder is rapidly brought up to accumulator pressure and immediately thereafter each cylinder is successively valved off from the accumulator and then communicated with the discharge groove 140 of the pintle. Continued rotation of the rotor with respect to the camming member H causes the ball pistons 118 to move inwardly in their cylinders 116 discharging the fluid into the discharge groove 142 through passageways 142 and 144 to the dis charge chamber of the pump. At the same time a small side stream is continuously supplied to the suction pressurizing nozzle 156 through the transverse drilling 148; and a second side stream of high pressure fluid is intermittently supplied to the accumulator 220 through the bleed down porting 230. The bleed down porting 230 is so positioned, constructed and arranged as to bleed pressure out of the discharge of the pump in amounts and at times which will otfset the pressure surges which are created when the individual cylinders 116 are connected to discharge-thereby smoothening out the flow of fluid discharged from the pump to alleviate the noise and vibration produced by pressure pulsations. For a more complete understanding of the manner in which this is accomplished reference may again be had to the explanation of FIGURES 5 through 13.

The pump shown in FIGURES 14 through 17 is a variable displacement pump which can control the amount of fluid delivered by the pump by changing the eccentricity of its camming member H with respect to its rotor F. The pump is designed to control the eccentricity of the camming member in a manner adapted to provide substantially constant discharge pressure. Pump discharge pressure is supplied to the inner end of the spool valve 196 of the control valve K-which pressure is opposed by the spring 212. When this pressure exceeds the setting of the spring 212, movement of the spool valve 196 permits pressure to be communicated with the control port 198, whereupon control pressure is exerted against the bottom end of the control piston 192. Upward movement of the piston 192 forces the slide I upwardlyproducing a shifting of the pin 196 in a direction causing the camming member H to move concentri cally with respect to the rotor member -F. The stroke of the ball pistons 118 is therefore reduced to cause a reduction in the displacement of the pump per rotor cycle, until such time as the quantity of fluid delivered by the pump equals the demand of the system to which the pump is connected at the set pressure as determined by the spring 212.

Although the invention has been described in considerable detail, '1 do not wish to be limited to the particular constructions shown and described; and it is my intention to cover hereby all novel adaptations, modifications, and arrangements thereof which come within the practice of those skilled in the art to which the invention relates.

I claim:

1. In a positive displacement pump: a stationary member having inlet and discharge passages and an accumulator reservoir therein, a rotatable member having sliding sealing engagement with said stationary member, at least one fluid chamber in one of said members, means for successively displacing liquid from said chamber and for causing a new supply of liquid to enter said chamber in timed relation to the movement of said rotatable member, said chamber being valved to said outlet passages when liquid is being displaced from said chamber and being valved to said inlet passages when liquid is caused to enter said chamber, and said chamber being isolated from the inlet and outlet passages intermediate the times they are valved to the inlet and outlet passages; said pump producing pressure surges in said discharge passages when said chamber is discharged thereto; first and second ports in the sliding sealing surface of one of said members, said sliding sealing surface of said one of said members having a recess therein communicating with said second port, a third port in the other of said members for successive registry with said first port and said recess, said first and third ports being constructed and arranged to communicate said chamber with said accumulator reservoir during the time that the chamber is isolated from the inlet and discharge passages, and said recess and said third port being constructed and arranged to conduct flow out of the discharge passages in a manner offsetting said pressure surges to smoothen out the fluid discharged from said pump.

2. In a rotary positive displacement pump of the sliding vane type: a body member having an internal chamber therein whose side surfaces are formed by surfaces of revolution positioned about an axis extending through said surfaces, a rotor member in said internal chamber, said rotor having side surfaces which are in sliding sealing engagement with said side surfaces of said body member, said members also having generally axially extending surfaces one of which is a surface of revolution and the other of which forms lobes and valleys which abut the generally axially extending surface of revolution to provide individual fluid confining chambers, a plurality of radial slots in the member having the generally axially extending surface of revolution, a sliding vane in each slot for sliding engagement with the lobes and valleys of the other member, said member having the generally axially extending surface of revolution being pro vided with a discharge pass-age positioned forwardly of each vane for receiving fluid forced out of said valleys by said vane and having inlet passages behind each vane for adding fluid to said fluid chambers, said'pump producing surges in discharge pressure as the fluid confining chambers are communicated to said discharge passages, a sink maintained at a lower pressure than said discharge port, said sink being suflflciently isolated from said dis charge port so that pressure fluctuations in said sink do not appreciably affect the pressure in said discharge port, and first and second ports in the adjacent sliding sealing side surfaces of said members for bleeding fluid out of said discharge passages to said sink, said ports being so positioned as to be brought into registry with each other when the fluid is being forced out of said discharge passages by said vanes, and being shaped and sized to produce a flow through the ports in an amount generally proportional to said surges to smoothen out the pressure level in said discharge passages.

3. In a rotary positive displacement pump of the sliding vane type: a body member having an internal chamber therein whose side surfaces are formed by surfaces of revolution positioned about an axis extending through said surfaces, a rotor member in said internal chamber, said rotor having side surfaces which are in sliding sealing engagement with said side surfaces of said body member, said members also having generally axially extending surfaces one of which is a surface of revolution and the other of which forms lobes and valleys which abut the generally axially extending surface of revolution to provide individual fluid confining chambers, a plurality of radial slots in the member having the generally axially'extending surface of revolution, a sliding vane in each slot for sliding engagement with the lobes and valleys of the othermember, said member having the generally axially extending surface of revolution being provided with a discharge passage positioned forwardly of each vane for receiving fluid forced out of said valleys by said vane and having inlet passages behind each vane for adding fluid to said fluid chambers, said pump producing surges in discharge pressure as the fluid confining chambers are communicated tov said discharge passages the pressure of which varies according to a generally predetermined pattern, said'body member also havingan accumulator reservoir therein which is sufficiently isolated from said discharge passages at all times so that pressure fluctuations in said reservoir produce substantially no effect in said discharge passages, a first port in said body member communicating said reservoir with one side surface of said pump chamber, a second port positioned in the adjacent side surface of said rotor in such manner as to periodically register with said first port during rotation of said rotor, said ports being constructed and arranged to pressurize one of said fluid chambers after it is filled with fluid and before it is communicated with said discharge passage, and a third port positioned in said adjacent side surface of said rotor in such manner as to periodically register with said first port, said third port being sized and shaped to conduct flow out of said one of said fluid chambers when it is communicating with said discharge passage at a rate and amount generally proportional to said pattern of said pressure surge to smoothen out the pressure of the fluid discharged from said discharge passages.

4. In a radial piston pump: a housing having an internal pump chamber therein, a pintle in said pump chamber, a generally annularly shaped rotor positioned in sliding sealing engagement around said pintle, said rotor having at least one cylinder chamber extending radially therethrough between its surface adjacent said pintle and its radially outer surface, a camming member eccentrically positionable around said rotor, a piston in each cylinder chamber adapted to abut said camming member in a manner causing each piston to move in and out with e a a 14 a r v respect to its cylinder chamber, said pintle having, suitable inlet passages for communication with each cylinder chamber as its piston moves radially outwardly and suitable discharge passages for communication with each cylinder chamber as its piston moves radially inwardly, said pump producing surges in discharge pressure as each cylinder chamber is communicated to said discharge passages the intensity of which varies according to a predetermined pattern, a sink maintained at a lower pressure than said discharge port, said sink being sufiiciently isolated from said discharge port so that pressure fluctuations in said sink do not appreciably affect the pressure in said discharge port, a first port in said sliding sealing surface of said pintle and communicating with said sink, a second port in said sliding sealing surface of said rotor and communicating with one of said cylinder chambers, said ports being so positioned as to be brought in registry with each other when the fluid is being forced out of said cylinder chamber, and being so shaped and sized as to produce a flow through the ports in an amount generally proportional to said pattern of said surges to smoothen out the fluid discharged from said discharge pass-ages.

5. -In a radial piston pump: a housing 'having an internal pump chamber therein, a pintle in said pump chamber, a rotor positioned in sliding sealing engagement around said pintle, said rotor having at least one cylinder chamber extending radially therethrough between its surface adjacent said pintle and its radially outer surface, a camming member eccentrically positionable around said rotor, a piston in each cylinder chamber adapted to abut said camming member in a manner causing each piston to move in and out with respect to its cylinder chamber, said pintle having suitable inlet passages for communication with each cylinder chamber as its piston moves radially outwardly and suitable discharge passages for communication with each cylinder chamber as its piston moves radially inwardly, said pump producing surges in discharged pressure as each cylinder chamber is communicated to said discharge passages the intensity of which varies according to a generally predetermined pattern, said body member also having an ac cumulator reservoir therein which is sufliciently isolated from said discharge passages at all times so that pressure fluctuations in said reservoir produce substantially no effect in said discharge passages, a first port in the sliding sealing surface of said pintle communicating with said accumulator reservoir, a second port in the adjacent sliding sealing surface of said rotor for periodic registry with said first port, said second port communicating with one of said cylinder chambers, said ports being constructed and arranged to pressurize said one of said cylinder chambers after it is filled with fluid and before it is communicated with said discharge passages, and a third port in said sliding sealing surface of the pintle for periodic registry With said second port, said third port being sized, positioned and shaped to conduct flow out of said one of said fluid chambers when it is communicating with said discharge passages at a rate and amount generally propor-tional to said pattern of said pressure surges to smoothen out the fluid discharged from said discharge passages.

6. For use with a positive displacement hydromechanical device having flow passages which are normally held at pressures above a predetermined level but in which there are rhythmic pressure pulsations; a pair of sliding sealing surfaces which are slid over each other in a prescribed path and in timed relation to said rhythmic pressure pulsations; a first port located in one of said pair of sliding sealing surfaces and which communicates with said passages during said pressure pulsations; a second port located in the other of said pair of sliding sealing surfaces and which communicates to a region of pressure which is below said predetermined level; one of said sliding sealing surfaces having a groove which communicates said first and second ports as said ports slide past each other, and said groove having a cross-section, length and position relative to said ports to provide a bleed flow out of said flow passages which substantially offsets said rhythmic pressure pulsations.

7. For use with a positive displacement hydromechanical device having flow passages which are normally held at pressures above a predetermined level but in which there are rhythmic pressure pulsations; a rotary valve comprising a pair of sliding sealing surfaces which are slid over each other about an axis of revolution in timed relation to said rhythmic pressure pulsations; a first port located in one of said pair of sliding sealing surfaces and which communicates with said passages during said pressure pulsations; a second port located in the other of said pair of sliding sealing surfaces and which communicates to :a region of pressure which is below said predetermined level; one of said sliding sealing surfaces having a groove which communicates said first and second ports as said ports slide past each other, and said groove having a cross-section, length and position relative to said ports to provide a bleed fiow out of said flow passages which substantially olfsets said rhythmic pressure pulsations.

8. In a positive displacement hydromechanical device having a casing member which houses a positive dis- 1 placement rotor member therein that rotates about an axis of revolution and that has side surfaces that are in sliding sealing contact with said casing, said casing further including flow passages which are normally held at pressures above a predetermined level but in which there are rhythmic pressure pulsations throughout the rotary cycle of said rotor: a first port located in said sliding sealing surface of said rotor; a second port located in said sliding sealing surface of said casing; one of said ports communicating with said flow passages during said pressure pulsations, and the other of said ports communicating to a region of pressure which is below said,

predetermined level; and one of said sliding sealing surfaces having a flow restricting recess which communicates said first and second ports as said ports slide past each other, said recess being so proportioned and positioned that the length of said recess between said ports and through which fluid flow takes place changes during the rotation of said rotor to vary the flow rate out of said flow passages in a manner generally offsetting said rhythmic pressure pulsations.

9. A positive displacement pump as set forth in claim 8, and wherein said recess extends to either side of said port in said one of said surfaces, whereby the flow through said ports gradually builds up to a maximum and there- 16 after gradually diminishes as said ports move past each other.

10. A positive displacement pump as set forth in claim 8, "and wherein said recess has changing cross sections throughout its length, whereby the flow through said ports builds up at a changing rate.

11. In a positive displacement hydromechanical device having a casing member which houses a positive displacement rotor member therein that rotates about an axis of revolution and that has side surfaces that are in sliding sealing contact with said casing, said casing further including flow passages which are normally held at pressures above a predetermined level but in which there are rhythmic pressure pulsations throughout the rotary cycle of said rotor: first porting comprising first and second spaced apart openings in the sliding sealing surface of one of said rotor and casing members, a recess in said surface of said one member connecting said first and second openings, second porting in the sliding sealing surface of the other of said members positioned to periodically register and communicate with said recess, one of said portings communicating with said flow passages during said pressure pulsations, and the other of said portings communicating to a region of pressure which is below said predetermined level, said recess being so positioned that said second porting opens into changing positions of said recess as the second porting and recess move past each other to vary the flow rate out of said flow passages in a manner generally ofisetting said rhythmic pressure pulsations.

References Cited in the file of this patent UNITED STATES PATENTS 1,087,181 Pitman Feb. 17, 1914 1,123,977 Baker et al. Jan. 5, 1915 2,423,271 Talbot July 1, 1947 2,504,841 Jones Apr. 18, 1950 2,743,090 Malan Apr. 24, 1956 2,786,422 Rosaen et -al Mar. 26, 1957 2,855,857 Chien-Bor Sung Oct. 14, 1958 2,855,858 Larsen et al Oct. 14, 1958 FOREIGN PATENTS 3,688 Great Britain of 1911 146,549 Great Britain July 5, 1920 288,420 Great Britain Apr. 12, 1928 385,192 Great Britain Dec. 22, 1932 433,488 Great Britain Aug. 15, 1935 1,117,494 France Feb. 27, 1956 UNITED STATES PATENT OFFICE @ERTIFICATE OF CORRECTION Patent Nee 3 OO7 Ll19 7 November 7 1961 Farlow Bo- Burt It is hereby certified that error appears in rule above numbered patentvrequiring correction and that the said Letters Patent should read as "corrected below v I Column 2 line 67 for radical read radial column 7,, line 39,, for *pressumized read pressurizlng column 9 line 559 for vposition' read piston e Signed and sealed this 29th day of May 1962,

'fEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

